Does my 05 FXDLI have the Rear cylinder cut-out system? And why does it run alot rougher when I grab the front brake? Some kinda sensor thing?

 

Not sure about yours but my 06 does.

 

should not run rougher when the brake is grabbed. Maybe need new pads or your rotor is warped? Also a good idea to clean the caliper.

 

My bad. Only when idleing it runs rougher. It's a cali. bike so maybe the smog crap?

 

Your bike shouldnt have the cut out
When it runs rough at idle, is it only doing that when you grab a handful of front brake while stopped?

And I cant remember, doesnt your bike have a carb? if so, its time to turn a screw. If its injected, its time to shoot some carb cleaner down the throat of the throttle body and clean up the IAC

 

that is just additional vibration transmission.

 

It is injected. It runs well and idles smooth without grabbing the front brake. While sitting still, idleing I can feel and see a distinct difference in vibration and tone when the front brake is pulled. When released it runs smooth. Almost like when you push the brakes on your car. It runs fine otherwise. There's always the chance i'm crazy too.

 

It shouldnt do that unless the vibration is being transmitted through the front end and up to your hands. The only thing I can think of that might be a cause would be the head bearings. When was the last time you had them adjusted and checked?
And yes, you're out of your tree

 

Head bearings? Is that next to the flux capacitor?

 

Well, your Harley does not have power brakes like your car does. There is no connection whatsoever from the front brake to the engine.

I can't think of any reason that would have any effect on engine idle quality. Unless there is some kind of short in the brake light wiring, and that effects the ECM module in some way. But I am just throwing that out there for one of the experts to think about.